A Washington appeals court has rejected the arguments of two British Columbia men serving life terms for killing a Seattle-area family.

Sebastian Burns and Atif Rafay argued their convictions for the July 1994 slayings of Rafay's parents and disabled sister should be thrown out because much of the evidence was from a so-called "Mr. Big" sting conducted by the RCMP.

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Sebastian Burns (back centre) and Atif Ahmad Rafay (third from left) are escorted by police in an image grab from a documentary, "Mr.Big," made by Burns's sister, Tiffany Burns. (Canadian Press)

Lawyers for Burns and Rafay argued details from such stings are not admissible in U.S. courts and the men, who were 18 at the time of the killings, were coerced into admitting to the murders.

A panel of three judges has ruled proper U.S. legal standards were applied in accepting the sting evidence, and the panel also says a lower court was right to decide Burns and Rafay confessed voluntarily.

The men are each serving three consecutive life terms for the murders, but have been spared the death penalty because of an extradition arrangement that returned them to Washington in 2001.

Rafay and Burns became friends while attending high school in West Vancouver and the jury at the men's six-month trial was told Rafay was motivated by money and planned the slayings while Burns carried them out.